Refrigerating apparatus



Feb. 2, 1943. .D. L. KAUFMAN 2,309,773

REFRIGERATING APPARATUS Filed March 29, 1941 2 Sheets-Sheet '1 "I B Q 7ZEIAITVNTOR. ,fiwvlawwmlfl D. L. KAUFMAN 2,309,773

REFRIGERATING APPARATUS Filed March 29, 1941 2 Sheets-Sheet 2 I v NVE QR.

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Patented Feb. 2, 1943 REFRIGERATIN G APPARATUS Daniel L. Kaufman, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application March 29, 1941, Serial No. 385,909

9 Claims.

This invention relates to refrigerating apparatus and more particularly to suction pressure control means.

The electric motors, which drive refrigerant compressors, become overloaded when the suction pressure becomes materially higher than the pressure for which they are designed. When the refrigerant load is light and the temperature surrounding the evaporating means is low the evaporator pressure and temperature decreases. It is often desirable to prevent the evaporator temperature from falling below freezing temperatures.

It is an object of my invention to provide a single device for preventing the compressor inlet pressure from becoming too high and for preventing the evaporator pressure from becoming too low. It is another object of my invention to provide a valve between the compressor inlet and the evaporator outlet which is closed by predetermined high and predetermined low suction pressures.

It is another object of my invention to provide a valve between the compressor inlet and the evaporator outlet which, when closed by a high suction pressure is responsive to compressor inlet pressure.

It is another object of my inventionto provide a valve between. the compressor inlet' and the evaporator outlet which when closed by a low suction pressure is responsive to evaporator out' 1 let pressure.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical sectional view taken along the line l-l of FigQZ of one form of valve embodying my invention, together with a diagrammatic representation of the remaining portions of one form of refrigerating system with which the valve may be used;

Fig. 2 is a sectional view taken along the line 2-2 of Fi 1;

Fig. 3 is a fragmentary view of the lower poi:- tion of the valve showing the valve closed by low suction-pressure; and

Fig. 4. is a view similar to Fig. 3 showing the valve closed by high suction pressure.

Briefly, I have shown a refrigerating system with a suction line valve which includes a sleeve valve and a bellows for operating the sleeve valve for withdrawing refrigerant from the evaporating means 22 through the suction conduit 24 and for forwarding the compressed refrigerant to a condenser 26 where the compressed refrigerant is liquefied. The liquefied refrigerant flows into -the evaporating means 22 under the control of a suitable expansion device 28. Although only one evaporating means is shown, others may be connected in parallel with the evaporating means 22. Refrigerant compressors compress vapor which is drawn from the evaporating means.

The higher the vapor pressure, the greater is the amount of vapor drawn into the compressor during each revolution. Thus, although the pressure differential upon opposite sides of the compressor may be reduced, the overall amount of work is increased by an increase in the suction or vapor pressure. To provide a motor of a sufficient size to operate the compressor under extremely high suction pressure conditions would be uneconomical, since too large a motor would be required for normal operation. Therefore valves have been used in the compressor inlet to limit the suction pressure to a definite amount so that a motor onlysuiiiciently large toamply take care of normal loads need be provided. In many refrigerating systems it is necessary to prevent the evaporator pressure from becoming so low as to cause freezing upon the evaporator surfaces. Valves have also been used for preventing the evaporator pressure from being reduced to such'anextent that the evaporator temperature falls below the freezing point.

I propose to perform these combined functions in a single valve. This valve designated by the reference character 30 includes a valve body 32 having aninlet 34 connected to the outlet of the. evaporating means 22 and an outlet 36 which is connected to the suction conduit 24 which in turn connects to the inlet of the compressor 20. Within the valve body 30 I provide a sleevevalve formed of a stationary outer sleeve 38 which fits in between the webs 40 and 42 within the housing 32, forcing the refrigerant to flow through the slots 44 provided in opposite sides of the sleeve 38. The top of the sleeve 38 is provided with a cap 46 which is pressed onto the top of the sleeve by a coil spring 48. A pin 58 may also be used for locking the sleeve 38 in position and preventing its rotation. The upper and lower ends of the sleeve 38 are located by wall portions of the valve body 30, as is shown in Fig. 1.

Within the outer stationary sleeve is an inner sleeve 52 which likewise has slots 54 which will register with the slots 44 when the inner sleeve is in the position shown in Fig. 1. This allows the refrigerant to flow straight through the valve substantially unimpeded. The lower end of the inner sleeve is provided with a spring retainer 56 which receives the upper end of a. compression type coil spring 58 seating on the bottom of the valve body 30. The upper end of the inner sleeve 52 is closed with the exception of a small passage 60 providing communication with i4 and an inner spring 16. These springs are re--- tained at their lower end by the closed end of the bellows 68 and at their upper end by a spring retainer 18. The tension of the springs 14 and 16 are adjusted by an adjusting screw 80 provided with a lock nut 82 by which the tension of the springs' 14 and 16 are adjusted.

The pressure within the interior of the inner sleeve 52 acts upon the bellows 68 and opposes the downward force of the springs 14 and 16. When the suction pressure is at the desired amount, there will be just sumcient force due to this pressure acting upon the bellows 68 to oppose the forces of the springs 16 to hold the inner sleeve 54 with its slots inregistration with the slots in the outer sleeve 38, as shown in Fig. l so that the refrigerant may flow freely through the valve to the compressor without material impedance.

Should the refrigerating load fail, the bellows 68 will expand due to the lowering of the pressure and to the force of the springs. This will cause the flow through the valve to be throttled so that less vapor will be withdrawn from the evaporating means. Further fallin pressure will cause the inner sleeve to move completely downto the bottom of its movement as shown in Fig. 3. It will be seen that the lower end of the outer sleeve 38 is provided with an aperture 84 which in Fig. 3 is in registration with an aperture 86 provided in the inner sleeve 52. This allows the vapor at the inlet side of the valve to communicate with the bellows chamber 66 and the bellows 68 so that the valve can again open as soon as the evaporator-pressure is suiliciently high to upwardly under the force of the compression spring 58 at its lower end. This will throttle the flow of refrigerant to the compressor so as to prevent the pressure at the inlet of the compressor 28 from rising above a certain maximum. Should the suction pressure rise further, the inner sleeve 52 will move upwardly to the position shown in Fig. 4 when the inner sleeve will completely close the slots in the outer sleeve 38. The operating pin 10 is provided with a transverse stop pin 88 which engages the lower end of the bearing boss 121:0 prevent excessive collapse of the bellows 68. The upward movement of the inner sleeve 52 is arrested by the engagement of its upper closed end with the cap 46 so as to prevent further upward movement of the inner sleeve 52 when the slots are closed as shown in Fig. 4. When the inner sleeve 52 reaches this position it has an aperture 90 which is in registration with an aperture 82 in the outer sleeve 38 so that under these conditions the bellows chamber 66 is connected by the passages 64 and 60 and the apertures 90 and 82 with the compressor inlet.

Thus when the compressor inlet pressure is too high, such as often occurs when the system is idle, no refrigerant will be permitted to flow to the compressor until the pressure at the compressor inlet reaches a certain amount which the compressor motor can safely handle. The volume of the refrigerant between the valve and the compressor inlet is so small that this amount will not overload the motor when the valve is closed regardless of the pressure therein. However, as soon as the pressure atthe compressor inlet is reduced sufiiciently, the bellows 68 will push the inner sleeve 52 downwardly to open the valve. When the valve is open, the pressure is substantially'the same on both sides except for the slight drop in pressure due to the friction of the refrigerant flowing through the valve. 4

Thus, I have provided a single valve operated by a single bellows which will keep the pressure of the refrigerant supplied to the compressor from going above a certain maximum and will prevent refrigerant from being drawn out of one or more evaporating means whenever the pressure falls below a certain minimum. The normal operating pressure for the valve may be readily adjusted by adjusting the screw to change the tension of the adjusting springs. In this way, a single suction line valve is made to perform two functions. This reduces the costof the system and also reduces the friction loss in the suction line.

While the form of embodiment of the invention as herein disclosed. constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus including compressor, condenser and evaporator mean connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a single pressure operated fluid motor for operating said valve means to open and closed positions, and means for subjecting the pressure operated fluid motor to evaporator pressure whenthe suction pressure is low and to compressor inlet pressure when the suction pressure is high.

2. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a single valve for closing the compressor inlet, and a single fluid motor for closing said valve upon a predetermined high compressor inlet pressure and also upon a predetermined low evaporator pressure.

3. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a single pressure operated fluid motor for operating said valve means to closed position upon a predetermined high suction pressure and upon a predetermined low suction pressure of the refrigerant passing through the valve means. i

4. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a single pressure operated means for operating said valve means to closed position upon a predetermined high suction pressure and upon a predetermined low suction pressure of the refrigerant passing through the valve means, and means for subjecting said pressure operated means to evaporator pressure when the valve means is closed. I V

5. Refrigerating apparatus including compressor, condenser and evaporator meansconnected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a single pressure operated means for operating said valve means to closed position upon a predetermined high suction pressure and upon a predetermined low suction pressure of the refrigerant passing through the valve means, and means for subjecting said pressure operated means to compressor inlet pressure when the valve means is closed.

6. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a single pressure operated means for operating said valve mean to closed position upon a predetermined high suction pressure and upon a predetermined low suction pressure of the refrigerant passing through the valve means, and means for subjecting said pressure operated means to evaporator pressure when the valve means is closed because of low suction pressure.

7. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a singl pressure operated means for -operating said valve means to closed position upon a predetermined high suction pressure and upon a predetermined low suction pressure of the refrigerant passing through the valve means, and

means for subjecting said pressure operated means to compressor inlet pressure when the valve means is closed because of high suction pressure. v

8. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means 10- cated in said circuit between the outlet of the evaporator means and the inlet to the compressor means, a pressure-operated means for operating said valve means to open and closed positions, and means for subjecting the pressureoperated means solely 'to evaporator pressure when the suction pressure is below a predetermined limit and solely to compressor inlet pressure when the suction pressure is above a certain limit.

9. Refrigerating apparatus including compressor, condenser and evaporator means connected in a closed refrigerant circuit, a valve means located in said circuit between the outlet of the evaporator means and the inlet to the compressor means, pressure-operated means responsive to the pressure of the refrigerant flowing through the valve means for operating the valve means to open and closed positions, and means effective when the valve means is closed due to high pressure conditions of the refrigerant for subj ecting the pressure-operated means substantially to the refrigerant pressure in the circuit portion between the valve means and the compressor inlet and effective when the valve means is closed due to low pressure conditions of the refrigerant for subjecting the pressure-operated -means substantially to the refrigerant pressure in the evaporator means.

DANIEL L. KAUFMAN. 

